Magneto assembly



Sept. 13 1938. P, E' MACK 2,129,953

MAGNETO AS SEMBLY Filed July 18, 1936 0 .P r'r .E. MED/f Patented Sept.13, 1938 PATENT OFFICE MAGNETO ASSEMBLY Perry E. Mack, Milwaukee, Wis.,Briggs & Stratton Corporation,

assignor to Milwaukee,

Wis., a. corporation of Delaware Application July 18, 1936, Serial No.91,331

12 Claims.

This invention relates to improvements in circuit breakers for internalcombustion engines and refers particularly to circuit breakers for usein small portable engines.

5. One of the objects of this invention is to provide a circuit breakerof unitary construction which may be assembled and tested as a unitprior to its assembly on the engine.

Another object of this invention is to provide a circuit breaker whichcan be more readily assembled and adjusted than devices of thischaracter heretofore in use.

Another object of this invention is to provide a circuit breaker of thecharacter described which is so designed that the contact pressure isnot altered upon wearing away of the contacts so as to insure agood'contact at all times.

Another object of this invention is to provide a circuit breaker of thecharacter described wherein the pivotal mounting for the switch arm isgreatly improved through the use of a V shaped notch or groove extendinglongitudinally of a mounting post.

And a further object of this invention is to provide a circuit breakerof the character described wherein the spring for the switch arm is soassociated therewith that the spring itself coacts with the switch armto hold these parts against relative displacement and to. damp outvibrations and chattering on the part of the switch arm.

With the above and other objects in view which will appear as thedescription proceeds, this invention resides in the novel construction,combination and arrangement of parts substantially as hereinafterdescribed and more particularly defined by the appended claims, it beingunderstood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete example of thephysical embodiment of the invention constructed accordingto the bestmode so far devised for the practical application of the principlesthereof, and in which:

Figure 1 is an end view showing part of a small portable internalcombustion engine with parts of its fly wheel broken away to illustratethe application of this invention thereto;

Figure 2 is a perspective view showing the various parts of the circuitbreaker disassembled;

Figure 3 is an enlarged detail section view through the switch armshowing the manner in which the spring is attached thereto;

Referring now more particularly to the acas companying drawing. in whichlike numerals indicate like parts throughout the several views, thenumeral 5 designates generally an internal combustion engine of thesmall portable type having a crank case which is closed at one end by amounting plate 6. 5

The plate 6 has a bearing 1 in which a crank shaft 8 is journaled.Mounted on the shaft 8 outwardly of the plate 6 is a fly wheel 9 inwhich a permanent ring magnet I0 is embedded with its poles ll exposedon the outer periphery of the 10 wheel. Coacting with the ring magnet tocomplete a magneto assembly is an armature core l2 having an inductioncoil l3 mounted thereon.

The core I2 is fixed to the mounting plate in such a manner that itspole pieces lie on an arc and are concentric to and spaced slightly fromthe outer wall of the fly wheel to be swept by the poles ll of the ringmagnet. Associated with the magneto assembly is a circuit breakerindicated generally by the numeral 14 and which forms the subject matterof this invention.

This circuit breaker is characterized by the fact that it is one unitaryassembly mounted on the engine as a complete unit so that it may betested and adjusted prior to its assembly on the engine.

It comprises a mounting bracket 15 stamped from sheet metal and having aflat attaching plate l6 which is secured to the mounting plate 6 byscrews l1 and I8. For purpose of adjustment to be hereinafter more fullydescribed, the screw l8 passes through an elongated hole I9 in theattaching plate.

Projecting out from the attaching plate l6 are two lugs or flanges and2| both substantially perpendicular to the plate IS. The lug 20 has astationary contact 22 mounted thereon but electricaily insulatedtherefrom. To facilitate connecting the stationary contact in theelectrical circuit a terminal 23 is electrically connected thereto. Theother lug 2| has its opposite side edges notched as at 24 and forms astationary spring support.

Fixed to and projecting out from he attaching plate I6 is a post 25which has a longitudinally extending substantially V shaped groove 26 inits side facing the stationary contact 22. The post 25 is preferablysecured to the plate I5 by a rivet formed as an integral part of thepost. The outer end of the groove 26 is closed by a washer 21 held inplace by a rivet also integral with the post.

The groove provides a fulcrum for a switch arm 28 one end 29 thereofwhich may be considered the base of the arm being received in thegroove. The width of this end 2! of the arm is equal to the length ofthe groove so that when engaged therein it is restrained againstlongitudinal motion but is free to swing toward and from the stationarycontact 22.

At its outer free end the arm 23 carries a movable contact 33 which isengageable with the stationary contact 22. The parts are so proportionedthat when the end 23 of the arm is engaged in the V shaped groove thetwo contacts 22 and 30 come together properly.

Like the mounting bracket, the switch arm 23 is stamped from sheet metaland is re-infonced by longitudinal flanges 3| on its side edges whichmerge into its wider end or base 29, and medially of its ends the armhas two spaced openings 32 and 33. These openings provide for theattachment of one end of a coiled tension spring 34, to the arm. Theother end of the spring is hooked onto the lug 2|. The spring 34 pullsthe switch arm towards the stationary contact 22 to provide contactpressure and also holds the end 23 of the arm in the groove 23.

The notches 24 in, the lug 2| hold the adjacent end of the spring in aplane which bisects the length of the groove 26 and as the point ofattachment of the other end of the spring to the switch arm is alsocentrally disposed with respect to the length of its bearing, the springholds the arm without the imposition of any sidewise strain, thusassuring proper engagement of the movable contact 30 with the stationarycontact 22.

To guard against any tendency on the part of the spring to rock on itsaxis and thereby impose force having an objectionable sidewise or lateracomponent on the switch arm, the attaching loop 35 which is hooked intothe opening 32 is so shaped and proportioned that at least the adjacentend coil 36 of the spring engages into the opening 33. In this way, thespring has a two point contact with the arm which serves to restrain thespring against rocking on its own axis and also serves to damp outvibrations and chattering on the part of the switch arm.

A double wall thickness at the edge of the opening 32 engaged by thespring loop 35 prevents excessive wear and cutting of the spring loopinto the edge of the opening. This double thickness is provided bybending back the metal struck from the arm to form the opening 32 intoan angularly extending tongue 31.

While the pivotal mounting of the switch arm provided by the engagementof the base end 29 in the longitudinal groove 23 provides a groundconnection between the arm and the mounting structure, a more positiveelectrical connection is obtained by a pigtail 33 soldered to the switcharm and secured to the mounting bracket as at 33.

As hereinbefore brought out the parts are so designed and proportionedthat the movable contact 30 will be properly aligned with the stationarycontact 22 when the base end 23 of the switch arm is engaged in the Vgroove in th P st.

However, in production it is probable that the post 23 and the flange orlug 20 will not be properly positioned with respect to each other so asto necessitate some adjustment to insure proper engagement between thecontacts. Such adjustment is facilitated by the provision of notches 40in the side edges of the attaching plate I. between the post and theflange 23 and similar notches 4| at the junction of the flange 23 withthe attaching plate.

These notches weaken the mounting bracket at these points so as tofacilitate twisting the same to effect the proper disposition betweenthe post 25 and the stationary conact.

As shown in Figure l, the switch arm is actuated by an insulated plunger42 slidabie in a radial bore 43 in the hearing I. One end of the plungeror pin 42 bears against the switch arm and its opposite end enters thebore of the bearing 1 to be engageable with the adjacent portion of thecrank shaft. A flattened part 44 on the crank shaft in line with theradial bore 43 allows the circuit breaker to close once each revolution.

Proper adjustment in the location of the circuit breaker assembly withrespect to the actuator pin 42 is obtained by loosening the screw II andmoving the entire assembly about the axis of the screw II. It is forthis purpose that the elongated slot I9 is provided.

From the foregoing description taken in connection with the accompanyingdrawing, it will be readily apparent to those skilled in the art towhich this invention appertains, that this invention provides anexceptionally compact circuit breaker mechanism, which, being a completeunit in itself, may be tested and adjusted prior to its attachment tothe engine and that by virtue of its exceptional simplicity it is wellsuited to economical manufacture.

What I claim as my invention is:

1. In a circuit breaker, a switch arm, a post having a longitudinalgroove to receive one end of the switch arm and pivotally support thearm, a contact carried by the opposite end of the arm, and a singlespring engaging the switch arm at a point between the pivotal supportand the contact whereby the spring force is divided to yield ly urge thearm toward one circuit controlling position and to hold the switch armin the groove.

2. In a circuit breaker, a post having a substan-- tially V-shapedlongitudinal groove, a switch arm carrying a contact at one extremitythereof and having its other extremity engaged in said V- shaped grooveso that the arm is pivotally supported on the post, a tension springhooked onto the arm near the post pulling the arm angularly toward thepost to retain the arm seated in the groove and to yieldingly hold thearm in circuit closing position, and means engageable with the armmedially oi its contact and the point of spring attachment for movingthe arm to open circuit position; Q

3. In a circuit breaker, a stationary contact, a switch arm having acontact at one end thereof for engagement with the stationary contact toclose a circuit, a pivotal support for the switch arm engaged by theopposite end of the arm, a tension spring attached to the arm near itspivotal connection with the support pulling the arm toward the supportand the stationary contact, and means engageable with the arm betweenits contact and the point of spring attachment for moving the sameagainst the tension of the spring to disengage its contact from thestationary contact.

4. In a circuit breaker, a mounting plate, a stationary contact on themounting plate. a switch arm having a movable contact at one endengageable with the stationary contact, a post ilxed on the plate andhaving a longitudinal groove facing the stationary contact to receivethe end of'the switch arm opposite the movable contact so as to providea pivotal mounting for the switch arm, 15

a fixed spring support carried by the plate adjacent the post and at thesame side of the arm the contacts are located, and a tension springhaving one end attached to the switch arm and the other end attached tosaid fixed support for yieldingly drawing the switch arm into circuitclosing position and for maintaining the same seated in the groove.

5. In a circuit breaker, a mounting plate stamped from bendable metaland having a fiat attaching surface and two spaced upstanding lugssubstantially perpendicular to the plane of the attaching surface, astationary contact carried by one of said lugs, a post fixed to thesupporting surface adjacent the other of said lugs, and having alongitudinal groove on its side facing the stationary contact, a switcharm having one end seated in said groove to be pivotally mountedenabling its outer free end to swing toward and from the stationarycontact, and a tension spring having one end attached to said other lugadjacent the post and its opposite end engaging the medial portion ofthe switch arm to yieldingly draw the switch arm toward the stationarycontact and toward the post.

6. In a circuit breaker, a stationary contact, a post having alongitudinal groove facing the stationary contact, a switch arm havingone end fulcrumed in said groove and its opposite end engageable withthe stationary contact, a spring connected to the arm to'apply springforce acting on the arm in a direction toward the post and stationarycontact so as to yieldingly maintain the arm engaged with the post andthe stationary contact, and means for holding the arm against edgewisemovement with respect to the post to preclude disalignment of its outerfree end with the stationary contact.

7. In a circuit breaker, a switch arm, a post having a longitudinalchannel to receive one end of the switch arm and provide a pivotalmounting therefor, a fixed support adjacent to the post, a tensionspring having one end hooked to the fixed support and its other endattached to the medial portion of the switch arm to yieldingly draw thearm toward the post and tending at all times to swing the arm in onedirection on its pivotal mounting, and means on the switch armengageable with the adjacent coils of the spring for holding the springcentrally with respect to the switch arm and for preventing chatteringof the arm.

8. In a circuit breaker, a pivoted switch arm, a tension spring havingone end attached to the arm to yieldingly urge the same in onedirection,

said spring pulling on the arm in a line forming an acute angle to thearm and having its hook which engages the arm so proportioned as todispose the end coil of the spring in contacting relationship to theswitch arm whereby the spring and arm are held against relativedisplacement and whereby vibrations and chattering on the part of theswitch arm are damped out.

9. In a circuit breaker of the character described, a pivoted switcharm-having two spaced holes medially of its length, and a coiled tensionspring for yieldingly urging the arm in one direction having anattaching loop passing through one of said holes and applying its forceon a line forming an angle sufiiciently acute with respect to the switcharm as to dispose its adjacent end coil in the other opening and therebyhold the spring against rocking.

10. In a circuit breaker, a pivotally mounted switch arm stamped fromsheet metal and having a hole located medially of its ends, a tensionspring to yieldingly urge the arm in one direction having an attachingloop passing through said hole, and means at the edge of said hole whichis engaged by the spring loop to re-inforce said edge.

11. In a circuit breaker, a stamped metal switch arm having a holemedial of its ends, a tension spring to yieldingly urge the arm in onedirection having a loop passing through said hole, and a doublethickness wall portion at the edge of said opening engaged by the springloop, said double thickness wall portion being formed by bending backthe metal out out from the arm to form the opening;

12. In a circuit breaker, a one, piece stamped metal mounting brackethaving a fiat attaching plate and an upstanding lugsubstantiallyperpendicular to the plane of the plate, a stationary contact carried bysaid lug, a post projecting perpendicularly up from the plate at adistance from the stationary contact and having a longitudinal groovefacing the stationary contact, a switch arm having a wide base at oneend thereof engageable in said groove to pivotally mount the arm withits outer end portion engageable with the stationary contact, springmeans for yieldingly urging the switch arm about its pivotal mounting ina direction toward the stationary contact, and said plate having notchesweakening its portion between the stationary contact and the post toenable twisting of the plate to dispose the post and stationary contactin exactly parallel planes in the event such adjustment is required.

PERRY E. MACK.

